Batoka Formation

Batoka Formation
Stratigraphic range: Lower Jurassic

Batoka basalt flows at Siyakobvu, Kariba District, Zimbabwe
Type Geological formation
Unit of Upper Karoo Group, Karoo Supergroup
Overlies Forest Sandstone Formation
Lithology
Primary Basalt
Other Sandstone
Type section
Named for Batoka Gorge, Zambezi river
Named by G.W. Lamplugh

The Batoka Formation is a geological formation in the Zambezi valley in Botswana, Zambia and Zimbabwe. It is mainly a volcanic unit, comprising mainly basalts, with Lower Jurassic sandstone that contain Vulcanodon fossils.[1]

Geology

Description

The formation is a volcanic unit, consisting mainly of high-titanium, low-potassium tholeiitic basalt flows[2][3][4] with small layers of aeolian sandstone and siltstone between some of the flows.[5][6]

Pillow lavas in Batoka Basalt, Siyakobvu, Kariba District, Zimbabwe

The lavas are dark, vesicular and porphyritic or massive basalts, with occasional pillows[7][8][9][10] although rare dacites and rhyolites have been reported from some areas of north-eastern Botswana.[11] The vesicular and massive basalts occur in alternating bands, with the vesicular bands usually being the top and base of each flow.[9][11] The basalt mineralogy consists of mainly of plagioclase, augite, magnetite, some ilmenite and volcanic glass. In the Hwange area, vesicles consist mostly of quartz, chalcedony or calcite,[9] though zeolites, such as stilbite, mesolite and laumontite, are dominant towards Victoria Falls and in the lower Deka valley[7] and are common in north-eastern Botswana.[11]

The basalt lavas are related to carbonatite intrusions in the Zambezi valley.[12]

Extent

The Batoka Formation is found in Botswana, Zambia, Zimbabwe, in the Mid-Zambezi, Mana Pools and Cabora Bassa basins[2][13][14]

Age

Lavas of the Batoka Formation have been dated at 179 to 180 Ma.[2]

Stratigraphy

The Batoka Formation is the uppermost formation in the Upper Karoo Group of the Karoo Supergroup, lying above the Forest Sandstone Formation.[13]

The Batoka Formation has been correlated to the Drakensberg Group of the Great Karroo Basin, South Africa[14] and the basalts of the Tuli Basin in Botswana and Zimbabwe.[15]

Fossils

Vertebrate fauna

Sauropodomorpha of the Batoka Formation
Genus Species Location Stratigraphic position Material Notes Images

Vulcanodon[1]

V. karibaensis[1]

Geographically located in the Bumi Hills area and the Sibilobilo Islands, in Kariba (District), Mashonaland West, Zimbabwe.[1][16]

"Partial skeleton [and] scapula."[17]

See also

References

  1. 1 2 3 4 Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Jurassic, Africa)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 535–536. ISBN 0-520-24209-2.
  2. 1 2 3 Jones, D. L.; Duncan, R. A.; Briden, J. C.; Randall, D. E.; MacNiocaill, C. (2001). "Age of the Batoka basalts, northern Zimbabwe, and the duration of Karoo Large Igneous Province magmatism". Geochemistry Geophysics Geosystems 2 (2): n/a. Bibcode:2001GGG.....2.1022J. doi:10.1029/2000GC000110.
  3. ↑ Ridgway, John; Money, N. J. (1981). "Karroo basalts from western Zambia and geochemical provinces in central and southern Africa". Geologische Rundschau 70 (3): 868. Bibcode:1981GeoRu..70..868R. doi:10.1007/BF01820167.
  4. ↑ Danielsen, Jens E.; Dahlin, Torleif; Owen, Richard; Mangeya, Pride; Auken, Esben (2007). "Geophysical and hydrogeologic investigation of groundwater in the Karoo stratigraphic sequence at Sawmills in northern Matabeleland, Zimbabwe: a case history". Hydrogeology Journal 15 (5): 945. Bibcode:2007HydJ...15..945D. doi:10.1007/s10040-007-0191-z.
  5. ↑ G. Bond (1973). "Palaeontology of Rhodesia". Rhodesia Geological Survey Bulletin 70.
  6. ↑ B.J. Wahl (1971). An Investigation of the Interbasaltic Sandstones in the Sibilobilo Islands, Kariba (Report). Unpublished B.Sc. Special Honours project, Department of Geology, University of Rhodesia (Zimbabwe), Harare, Zimbabwe.
  7. 1 2 G.W.Lamplugh (1907). "The Geology of the Zambezi Basin around the Batoka Gorge (Rhodesia)". Quarterly Journal of the Geological Society 63: 162–216. doi:10.1144/GSL.JGS.1907.063.01-04.14.
  8. ↑ B. Lightfoot (1914). "The Geology of the North-western part of the Wankie Coalfield". Southern Rhodesia Geologial Survey Bulletin 4.
  9. 1 2 3 B. Lightfoot (1929). "The geology of the Central Part of the Wankie Coalfield". Southern Rhodesia Geologial Survey Bulletin 15.
  10. ↑ B. Barber (1994). "Notes on the isotopic dating of Karoo and younger lavas from the Zambezi valley, and implications for sedimentation". Annals of the Zimbabwe Geological Survey 17: 19–23.
  11. 1 2 3 R.A. Smith. The lithostratigraphy of the Karoo Supergroup in Botswana (Report). Geological Survey Department, Ministry of Mineral Resources and Water Affairs, Republic of Botswana.
  12. ↑ K.L. Walsh, P. Hall and D.J. Hughes (1999). "Major and trace element geochemical characteristics of Karoo basaits in Zimbabwe, providing evidence for the origin of spatially related carbonatites". Journal of African Earth Sciences 28 (4S1): 84. Bibcode:1999JAfES..28....1. doi:10.1016/S0899-5362(99)00028-7.
  13. 1 2 Nyambe, Imasiku A.; Utting, John (1997). "Stratigraphy and palynostratigraphy, Karoo Supergroup (Permian and Triassic), mid-Zambezi Valley, southern Zambia". Journal of African Earth Sciences 24 (4): 563. Bibcode:1997JAfES..24..563N. doi:10.1016/S0899-5362(97)00081-X.
  14. 1 2 Catuneanu, O.; Wopfner, H.; Eriksson, P.G.; Cairncross, B.; Rubidge, B.S.; Smith, R.M.H.; Hancox, P.J. (2005). "The Karoo basins of south-central Africa". Journal of African Earth Sciences 43: 211. Bibcode:2005JAfES..43..211C. doi:10.1016/j.jafrearsci.2005.07.007.
  15. ↑ Rogers, Raymond R.; Rogers, Kristina Curry; Munyikwa, Darlington; Terry, Rebecca C.; Bradley s.Singer (2004). "Sedimentology and taphonomy of the upper Karoo-equivalent Mpandi Formation in the Tuli Basin of Zimbabwe, with a new 40Ar/39Ar age for the Tuli basalts". Journal of African Earth Sciences 40 (3–4): 147. Bibcode:2004JAfES..40..147R. doi:10.1016/j.jafrearsci.2004.11.004.
  16. ↑ M.A. Raath (1972). "Fossil vertebrate studies in Rhodesia: a new dinosaur (Reptilia: Saurischia) from near the Trias-Jurassic boundary". Arnoldia 5.
  17. ↑ "Table 13.1," in Weishampel, et al. (2004). Page 261.


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